Where Did All The Watermelon Seeds Go?

Many people think of the seedless watermelons popping up at grocery stores and markets everywhere in the last few years as a marvel of modern scientific technology. In fact, more than 60 percent of watermelon shoppers seek this smoother pink flesh, and the numbers are increasing every year, according to a recent survey done for the National Watermelon Promotion Board.

The seedless melons sure are easier to eat and cut up for fruit salads. But they somehow don't taste the way they did when seed-spitting contests were the highlights of our summers.

So here at The Salt we wondered, are watermelons destined to go the way of supermarket tomatoes, where flavor has been sacrificed for convenience?

Before we get to that, a quick science lesson: How do you get a seedless watermelon? In a word - colchicine. The chemical, derived from the crocus and developed to treat and prevent gout since ancient Egypt, has found a niche in plant biology because of the way it impacts chromosome development.

According to North Carolina State University's research blog, The Abstract, when young watermelon plants are treated with colchicine,

"... the eggs in the flowers develop with two sets of chromosomes (2n), instead of one. When the eggs are pollinated, they create triploid cells ... These cells are capable of maturing into fruit, but the seeds in that fruit are not genetically viable – so they can't be fertilized and develop the hard, black [seed coat]."

Hence, you get the little thin white "seeds" that you see in seedless watermelon, as opposed to the hard black ones good for spitting into your sister's hair (not that I'm admitting anything here).

Basically, "it's the watermelon version of the mule," as our colleague Andrea Seabrook put it a few years back. And that's what the public demands, so that's what most producers are growing.

That brings us back to the question of what these immature seeds do to flavor.

Who can blame us when Mark Twain's Pudd'nHead Wilson said it so eloquently:

"It is the chief of this world's luxuries, king by the grace of God over all the fruits of the earth. When one has tasted it, he knows what the angels eat. It was not a Southern watermelon that Eve took; we know it because she repented."

What really matters with watermelons is when they were harvested and how far they've traveled, Wehner says.

In a fair taste test between seeded and seedless watermelons picked fresh from a field, "the triploids always win," he says. The triploids — the seedless ones — have three sets of genes instead of two, so any genes that affect sweetness, flavor, and texture are more likely to be expressed.

And, he adds, some people prefer the caramel flavor of the Sugar baby variety, while others like the straight watermelon flavor of Crimson sweets. So the definition of "sweet" is variable.

"Think about where we started back in 6,000 years ago," Wehner says. "Watermelons came from southern Africa - they were white, hard, late maturing, low-yielding, and full of seeds."

While the supermarket may only have one or two varieties of the red seedless ones these days, seed catalogs and farmers' markets offer dozens more.

I feel an experiment coming on.

Copyright 2012 National Public Radio. To see more, visit http://www.npr.org/.